Treating corrosive oils



Patented May 25, 1943 UNITED STATES TREATENG CORROSIVE OILS Charles A. Cohen, Elizabeth, N. J., assignor to Standard Oil Development Company, a corporation of Delaware No Drawing. Application December 2'7, 1939, Serial No. 311,117

11 Claims.

This invention relates to an improved process for refining hydrocarbon oils. More particularly, it is concerned with the treatment of oils of the white oil type such as medicinal oils, transformer oil, insecticide base oils, refrigerator oils, or cosmetic oils and lubricating oils like spindle oil or motor oil which have during the process of their refinement been subjected to the action of fuming sulfuric acid.

Highly acid treated oils or white oils are prepared by the drastic treatment of a hydrocarbon oil having a viscosity in the range of 30-1000 seconds Saybolt at 100 F. with fuming sulfuric acid, followed by separating the acid sludge from the oil, neutralizing the acid oil with an alkali, removing the alkali sulfonates from the oil by dilute alcohol or other solvents and steaming the oil to remove the solvent and other volatile constituents. The oil at this stage is known as a neutral oil and varies in color from to Saybolt. It is then finished by percolating it thru a bed of absorbent clay to give a finished white oil of Saybolt in color.

Many such oils are, however, corrosive in character and will cause the corrosion of copper in less than two hours when subjected to the cop-v per strip test. This test consists in polishing a strip of copper measuring to 3" withtripolii or other fine abrasive, immersing the copper strip in a sample of the oil to be tested and heating for from 2 to 3 hours in a steam bath at a temperature of 212 F. The results are rated numerically as follows: No. 1 shows no change in appearance of the original copper strip; No. 2 shows .a slightly discernible yellow color but is still pass-able; No. 3, which fails, shows a pronounced bronze coloration; No. 4 shows a deep bronze color and No. 5 is blue-black. Ordinarily, oils which have failed to pass the copper strip test have had to be recycled thru the acid treatment in an attempt to make them less corrosive. At times it has been necessary to recycle the corrosive oils thru the acid treat three or four times before an acceptable copper strip test is obtained upon them.

Some success has been had in treating finished white oils to improve their copper strip test by the use of calcium or magnesium hydroxide. However, this method is not applicable to medicinal white oils because oils treated with these reagents acquire an objectionable taste. Also, the quantity of calcium and magnesium hydroxide used is bulky and its removal necessitates additional handling of the finished oil which ineases the possibility for contamination. In

addition, there are times when in order to obtain good copper strip tests by the calcium and magnesium hydroxide, it has been necessary to give the oil several treatments with these hydroxides.

It has now been found that acid treated oils which fail to pass the copper strip test after finishing by percolation thru clay, because of their corrosive characteristics, may be treated in the neutral condition in such a manner that all corrosiveness is prevented. This treatment consists in adding to the oil an organic compound of an alkaline earth metal, which is hydro or thermally decomposable to yield a volatile organic compound and the hydrated oxide of an alkaline earth metal, and blowing either with hot air freed of carbon oxides, a mixture of hot air free of carbon oxides and water vapor or steam for a time sufficient to efiect decomposition of the metallo-organic compound and removal of the volatile constituents liberated by the decomposition of the metallo-organic compound and to precipitate the hydrated oxide of the alkaline earth metal, then filtering out the precipitate and percolating the oil thru a serpent material. The organic compound which reacts with the alkaline earth metal to yield the metallo-organic compound used to treat the neutral oil may be an alcohol, a ketone, or any organic compound containing a labile hydrogen. Materials of this type are calcium or magnesium alcoholates which can be prepared in accordance with the method set forth in my copending application No. 311,322, filed December 28, 1939. The proportions of metallo-organic compounds to be used with the neutral oil should be such as to yield alkaline earth oxides in the range between 2 and 25 lbs. perthousand gallons of oil. During the treatment, the oil is maintained at a temperature between and 150 0., C. being the preferred temperature. Agitation is depended upon to secure contact between the neutral oil and the metallo-organic compounds. This agitation is provided by the passage of the hot air or steam thru the oil either with or without the aid of a mechanical agitator. The length of time of contact between the metallo-organic compound and the oil is immaterial. However, the mixture must be blown with either hot air or steam for a length of time sufficient to decompose the metallo-organic compound. This decomposition of the metallo-organic compound with hot air or steam may ordinarily be accomplished in from 15 to 30 minutes. It is advantageous at this joint to remove the precipitated alkaline earth oxide in its hydrated form and this can be done by allowing the oil to settle, by centrifuging or by filter pressing. The filter may be of the blotter, plate and frame or rotary type and a commercial siliceous filter aid may be used either as a precoat on the filter or mixed with the oil before filtering. After the removal of the hydrated oxide the oil is found to be much improved in color and for some grades of oils no further treatment designed to improve color is necessary. For highly refined oils such as medicinal oils which mus-t be colorless, tasteless and odorless, further treatment with a sorptive material such as Fullers earth, bauxite, attapulg'us clay or activated charcoal may be required. This may be done by contacting the oil with the sorptive material in a powdered form or by percolation thru a bed of granular sorptive.

The following examples are given for the purpose of illustrating the invention:

Example 1 1.000 gallons of neutral white oil, viscosity 55 secs. Saybolt at 100 F. and plus 17 Saybolt color was heated to 125 C. 11.7 lbs. of calcium isopropylate Ca(OC3I-lq) 2 was then added to the hot oil; The calcium isopropylate could b added either as a dry powder, as a slurry in isopropyl alcohol in which it is slightly soluble, or as a dispersed solid in oil of the same viscosity as the oil to be treated. The mixture was then air- Example 2 1000 gallons of neutral white oil, viscosity 55 secs. Saybolt at 100 F. and +17 Saybolt color was treated as in Exampl 1 using aslurry of magnesium isopropylate Mg(OC3H7)2 equivalent 0022.5 lbs. of magnesium isopropylate. After treatment with magnesium isopropylate and the removal thereof, the oil had a +29 Saybolt color and a pass copper test. The finished oil had a +30 up Saybolt color and gave a pass copper test.

Example 3 1000 gallons of neutral white oil, viscosity 85 secs. Saybolt at 100 F. and +1 Saybolt color was tested and found not to pass the copper strip test. The oil was then treated as in Example 2 using the same proportions of magnesium isopropylate. The treated oil had a +16 Saybolt color and gave a copper pass test and after percolation thru clay had a +30 up Saybolt color and gave a pass copper test.

The foregoing disclosure and examples are given for the purpose of illustration only and are not tofbe construed as in any way limiting the invention.

What is claimed is:

1. Theprocess of reducing th color and cor- The treated oil was then filter pressed rosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state with the anhydrous reaction products of metallic magnesium and an organic compound possessing a replaceable hydrogen selected from the group consisting of an alcohol and a ketone.

2. The process of reducing the color and corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral condition with the anhydrous reaction products of an alkaline earth metal and an alcohol.

3. The process of reducing the color and corrosivness of acid-treated oils on copper which comprises treating the oil in its neutral condition with the anhydrous reaction products of an alkaline earth metal and an anhydrous alcohol.

4. The process of reducing the color and corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state with an anhydrous alkaline earth isopropylate.

5. The process of reducing the color and corrosivness of acid-treated oils on copper which comprises treating the oil in its neutral condition with anhydrous calcium isopropylate.

6. The process of reducing the color and corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral condition with anhydrous magnesium alcoholate.

7. The process of reducing the color and corrosiveness of acid-treated oils on copper which comprises treating the oil in its neutral state with anhydrous magnesium isopropylate.

8. The process of improving the color and copper strip test of an acid-treated mineral oil which comprises heating the oil in its neutral state to from -150 (3., adding to the oil anhydrous calcium alcoholate in an amount equivalent to from 2 to 25 lbs. of calcium oxide per thousand gallons of oil, decomposing the calcium alcoholate, removing the hydrated oxide and percolating the oil thru clay.

9. The process of improving the color and copper strip test of a mineral white oil which com prises heating the oil in its neutral state to 0., adding to the hot oil anhydrous calcium isopropylate in an amount equivalent to from 2 to 25 lbs. of calcium oxide per thousand gallons of oil, decomposing the calcium isopropylate, removing th hydrated calcium oxide and percolating the oil thru clay.

10. A process of improving the color and copper strip test of a, mineral white oil which comprises heating the oil in its neutral condition to 125 0., adding to the hot oil anhydrous magnesium isopropylate in an amount equivalent to from 2 to 25 lbs. magnesium oxide per thousand gallons of oil, decomposing the magnesium isopropylate, removing the'hydrated oxide and per colating the oil thru clay.

11. A process of improving the color and copper strip test of a medicinal white oil which comprises heating the oil to 125 0., adding to the hot oil anhydrous magnesium isopropylate in an amount equivalent to from 2 to 25 lbs. of hydrated oxide per thousand gallons of oil, decomposing the magnesium isopropylate, removing the hydrated lime and percolating the oil thru clay.

CHARLES A. COHEN. 

